std::ranges...:find_next,(3)

💅 NAME 💅

std::ranges::chunk_by_view::find_next — and also std::ranges::chunk_by_view::find_next bestie, the manpage really said it twice 💀 — this is one of those internal helper things (/*find-next*/ and its little sister /*find-prev*/) from the C++ Standard Libary (yes that's the spelling up top, we keep it 🎀).

---

✨ SYNOPSIS ✨

constexpr ranges::iterator_t<V>                      (since C++23)
    /*find-next*/( ranges::iterator_t<V> current );  (exposition only*)

That (since C++23) is doing a lot of heavy lifting ok — this is new-new 🔥. And the (exposition only*)? That means she's an exposition-only icon, iykyk — she exists so the standard can explain herself, not so you can call her directly 🫶.

---

🌸 DESCRIPTION 🌸

Ok so picture this: she finds the next chunk. That's it, that's the vibe.

Let base_ and pred_ be appropriate underlying data-members of chunk_by_view ✨.

Functionally she's equivalent to:

return ranges::next
(
    ranges::adjacent_find
    (
        current, ranges::end(base_), std::not_fn(std::ref(*pred_))
    ),
    1, ranges::end(base_)
);

Like, literally that. No cap. She does an ranges::adjacent_find with std::not_fn(std::ref(*pred_)) from current to ranges::end(base_), then ranges::next skips one past it, bounded by ranges::end(base_). Slay 💅

⚠️ The behavior is undefined if pred_.has_value() is false before the call to this function. Like — genuinely undefined, not "undefined in a cute way". Check your pred_ first, bestie 😭

Used in the following non-static member functions:

• ranges::chunk_by_view::iterator::operator++

So when you increment that iterator, this is the girl working behind the scenes 👑

---

💖 PARAMETERS 💖

• current — the iterator to current element in adapted view 🦋

---

🎀 std::ranges::chunk_by_view::prev 🎀

Ok different function, same energy. Here's her flexibility:

constexpr iterator_t<V>
                                                      (since C++23)
    /*find-prev*/( ranges::iterator_t<V> current )  (exposition only*)

        requires ranges::bidirectional_range<V>;

Note the requires ranges::bidirectional_range<V>; — she only shows up for bidirectional ranges, because obviously you can't go backwards through something that doesn't go backwards 🙈

She finds the previous chunk ⭐

Let base_ and pred_ be appropriate underlying data-members of chunk_by_view.

She returns an iterator i in the range [ranges::begin(base_), current) such that:

• ranges::adjacent_find(i, current, std::not_fn(std::ref(*pred_))) is equal to current, and
• if i is not equal to ranges::begin(base_), then bool(std::invoke(*pred_, *ranges::prev(i), *i)) is false.

Both conditions. Not one, not the other — both. Periodt 💜

💀 The behavior is undefined if before the call to this function current == ranges::begin(base_) or pred_.has_value() != true. So don't call her at the very start, and don't call her with an empty pred_. That's the whole warning. Respect it 😤

Used in the following non-static member functions:

• ranges::chunk_by_view::iterator::operator--

Decrement squad represent 🌈

---

🍓 PARAMETERS 🍓

• current — the iterator to current element in adapted view.

---

✨ that's the whole page bestie, go forth and chunk responsibly ✨

Sign-off vibes: this gem dropped from http://cppreference.com on 2024.06.10, filed under std::ranges...:find_next,(3) 💖🦋🎀